Root responses to low nutrients in ® Capsella bursa-pastoris & Arabidopsis thaliana Jennifer Greig Breadalbane Academy, Aberfeldy Nuffield Bursary Project supervised by Alison Karley and Tracy Valentine at the Scottish Crop Research Institute, Invergowrie, Dundee July-August 2005
1. Project aims 2. Background 3. Methods The aim of the project was to investigate root responses to low Arabidopsis is a model plant Six Capsella lines were nutrients in Capsella bursa-pastoris and Arabidopsis thaliana. To for genetic studies and chosen to represent a investigate the responses we looked at root and root hair growth Capsella is a closely related range of flowering and border cell production in response to low concentrations of arable weed. Root hairs are times. Eight Nitrogen and Phosphorus. outgrowths from epidermis Arabidopsis lines were cells creating a large surface chosen with mutations area that aids the plant in in genes that might obtaining nutrients, and affect border cell border cells are thought to production. The low attract and stimulate growth phosphorus (Low P) in micro-organisms and medium was different repel and prevent the from the Control in that growth of others. This study phosphate nutrient was is unique because nobody omitted and the low really knows the function of nitrogen (Low N) had root border cells under N-containing nutrients these nutrient conditions. diluted by 1/10. Arabidopsis Capsella
4. Capsella root lengths 5. Capsella root hair lengths
Low N caused root length to increase relative to Low P decreased root hair length and low N increased root control and Low P caused root length to hair length relative to the control (Figure 2). decrease (Figure 1).
60 350
300 50 250 40 Low N 200 30 Control 150
Root length in mm Low P 20 Low N Root hair outgrowths 100 Root hair length in µm Control 10 50 Low P
0 0 156-230 469-260 474-558 280-509 798-189 937-71 930-161 158-418 156-230 469-260 474-558 280-509 798-189 937-71 930-161 158-418 Plant type Plant type
Figure 1 Root length in Capsella in response to Low N and Low P Figure 2 Root hair length in Capsella in response to Low N and Low P.
6. Border cell production by Capsella and Arabidopsis
There was 5.0 4.5 significant 4 variation between 4.0 3.5 3 3.0 Low N Low N the different plant 2.5 Control Control Low P 2 lines (Figure 3 and 2.0 Low P Arabidopsis root with no border cells 1.5 4). Low P 1.0 1 Median score per root tip per root Median score 0.5 treatment ip number of cells per root Average 0.0 0 156-230 469-260 474-558 798-189 930-161 158-418 Line 1 Line 2 Line 3 Line 4 Line 5 Line 6 Line 7 Line 8 increased border Plant line Plant Line cell production in Figure 3 Median border cell score (1=no cells, Figure 4 Mean number of border cells per root in both plant 5=root covered in cells) in Capsella in response Arabidopsis in response to Low N and Low P. to Low N and Low P. species, and Low
N had no effect. Arabidopsis root with many border cells
7. Conclusions
12The low N treatment increases Low P treatment stimulates border cell production 3This study has provided important information about root and root hair length while in both Arabidopsis and Capsella and the low N how plant roots respond to low soil nutrients, which the low P decreases root and decreases root border cell production with Capsella might help future research to understand the processes root hair length. and increases it slightly with Arabidopsis. and genes controlling nutrient uptake by plants.